On January 2, 1980, in response to the Soviet invasion of Afghanistan in December 1979, President Jimmy Carter asked the Senate to suspend the SALT II nuclear weapons treaty and recalled the US ambassador to Moscow. These actions sent a message that the era of détente and friendlier diplomatic and economic relations established between the United States and the Soviet Union during the administration of President Richard Nixon (1969-1974) was over.
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Carter feared that the Soviet invasion of Afghanistan, in which about 30,000 troops entered the capital Kabul and established a puppet government, would threaten the stability of strategic neighboring countries such as Iran and Pakistan and could lead to the USSR gaining control of much of the world's oil supplies. The White House described the Soviet actions as a “serious threat to peace”. Carter asked the Senate to delay ratification negotiations for SALT II, the nuclear arms treaty that he and Soviet Premier Leonid Brezhnev had already signed, and the president recalled the U.S. ambassador to Moscow, Thomas J. Watson, back to Washington for "consultations" to make it clear to the Kremlin that military intervention in Afghanistan was unacceptable.
When the Soviet Union refused to withdraw from Afghanistan, America halted some key exports to the USSR, including grain and high technology, and boycotted the 1980 Summer Olympics, held in Moscow.
The United States also began covertly subsidizing anti-Soviet fighters in Afghanistan. During Ronald Reagan's presidency in the 1980s, the CIA secretly sent billions of dollars to Afghanistan to arm and train the mujahideen rebel forces fighting the Soviet Union. This tactic succeeded in helping to drive out the Soviet Union, but it also gave rise to the despotic Taliban regime and Osama bin Laden's terrorist organization "Al Qaeda."
In 1980, Jimmy Carter lost the presidency to Ronald Reagan, who favored a more aggressive anti-communist foreign policy. Reagan called the USSR an "evil empire" and believed it was America's responsibility to save the world from Soviet repression. He dramatically increased U.S. defense spending and accelerated a nuclear arms race with the Soviet Union, whose weak economy ultimately prevented them from competing. The Soviet Union collapsed in 1991.